Re: [PATCH v2] sched_ext: Rebuild fair weight on ext to fair switches
From: Peter Zijlstra <peterz@infradead.org>
Date: 2026-05-28 09:25:51
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From: Peter Zijlstra <peterz@infradead.org>
Date: 2026-05-28 09:25:51
Also in:
lkml
On Thu, May 28, 2026 at 10:53:54AM +0800, Zicheng Qu wrote:
2. Rebuilding `p->se.load` from fair's `switching_to` hook. This is the most natural place semantically, since the task is entering fair and fair prepares its own state before enqueue. My only concern was that, for non-ext -> fair paths, `__setscheduler_params()` may have already updated `p->se.load` through `set_load_weight(p, true)`, so calling `set_load_weight(p, false)` unconditionally here can be redundant logically. Functionally, though, it is harmless.
Right. We can worry about optimizing this if there's ever a report. I don't expect this to be noticeable much. If anything, the PI code would be the one to trip this most often I think.